From: Todd Benson <caduceass@...>
Date: 2007-10-01T06:52:21+09:00
Subject: Re: ObjectSpace reveals order?

On 9/29/07, Eric Hodel <drbrain@segment7.net> wrote:
> On Sep 28, 2007, at 18:18 , Todd Benson wrote:
>
> > If I do...
> >
> > ObjectSpace.each_object { |o| puts o; gets }
> >
> > will it give me the consecutive order of the loading of the objects
> > (i.e. the time order that memory is allocated on the heap)?
>
> Well, its kinda backwards*:
>
> $ cat test.rb
> items = ['a', 'b']
>
> ObjectSpace.each_object do |o|
>    p o.object_id => o
> end
>
> $ ruby test.rb | head -3
> {1001920=>"b"}
> {1001930=>"a"}
> {1001940=>["a", "b"]}
>
> [] was allocated first, then 'a', then 'b', not the other way around.

Ok, logistically this makes sense.  I see.

>
> * This example was too small to invoke the garbage collector, so it
> will be in reverse order.  With garbage collection you aren't
> guaranteed any ordering.
>
> > Or is it a tree structure underneath or something strange like that?
>
> You can infer the structure of ruby's heap if you make enough
> objects.  Replace items = ['a', 'b'] with ('a'..'aaa').to_a and add
> GC.disable

OK.  Got ya.

> Ruby's heaps look something like:
>
> heaps = [
>    [ ... ], # objects live in here
>    ...      # more arrays of objects, as necessary
> ]
>
> This was on OS X.
>
> > Why do I get String objects right off the bat like...
> >
> > ' does not evaluate to a gem specification
>
> You have RUBYOPT=-rubygems

Thanks!

Todd